Rationale of Study: Achromatopsia or complete color blindness is an autosomal recessive condition that is rare in the general population (<1/30,000), but very common among the people of Pingelap (1/14), who came from an island in Federated States of Micronesia. The identification of the disease-causing gene will lead to a better understanding of how we see color and how retinal cones function. Identification of the gene will aid in genetic counseling and may lead to potential treatments. In order to identify the gene, families which segregate achromatopsia need to be studied. Goals: The goals of this study are: to localize the second gene responsible for achromatopsia and to isolate it. In order to meet these goals families with achromatopsia must be studied.